1 Topic by SteveInAkron

  • SteveInAkron
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Topic: Single user is having external email bounced as no user

==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.8 MARIADB edition
- Deployed with iRedMail Easy or the downloadable installer? Installer
- Linux/BSD distribution name and version: Debian 12
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): NginX
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

A single user from a domain is having all mail to them bounce with a message similar to the below.  It is only for this single user.  The user can receive mail from other users on the server.

2025-10-03T15:54:06.027957-04:00 iredmail postfix/smtpd[1810471]: NOQUEUE: reject: RCPT from xxxxx.yyyyy.net[w.x.y.z]: 550 5.1.0
<double-bouncex@yyyyy.net>: Sender address rejected: User unknown; from=<double-bounce@yyyyy.net> to=<tracy@zzzzzz.ccc> proto=ESM
TP helo=<xxxxx.yyyyy.net>

I was going to add the user again, but I didn't want to loose the email.

----

Spider Email Archiver: On-Premises, lightweight email archiving software developed by iRedMail team. Supports Amazon S3 compatible storage and custom branding.

2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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Re: Single user is having external email bounced as no user

Does user "tracy@zzzzzz.ccc" exist? If not, it's expected that Postfix rejects it.

3 Reply by SteveInAkron

  • SteveInAkron
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Re: Single user is having external email bounced as no user

User exists. The domain was transferred to the server about a month ago, and has been working fine until 9:30AM yesterday. 

The issue is with the interaction between the external SPAM filter service and my server.  I changed the MX record for the domain to eliminate the external filter for now, and it is working.  I use the external filter for a few other domains that are working fine. 

I had debug_peer_list on for the domain before I changed the MX, but didn't see anything obvious. 

I did change the mailbox quota for that user the day before, but I cannot see how that would have an effect.

4 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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Re: Single user is having external email bounced as no user

Please show us full console output of commands below (replace tracy@zzzzzz.ccc by real email address):

cd /etc/postfix/mysql/
for i in $(ls *.cf); do echo $i; postmap -q tracy@zzzzzz.ccc mysql:./$i; done

5 Reply by SteveInAkron (edited by SteveInAkron 2025-10-07 21:40:08)

  • SteveInAkron
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Re: Single user is having external email bounced as no user

Here's the output of the command:

catchall_maps.cf
domain_alias_catchall_maps.cf
domain_alias_maps.cf
recipient_bcc_maps_domain.cf
recipient_bcc_maps_user.cf
relay_domains.cf
sender_bcc_maps_domain.cf
sender_bcc_maps_user.cf
sender_dependent_relayhost_maps.cf
sender_login_maps.cf
tracy@zzzzzz.ccc
transport_maps_domain.cf
transport_maps_maillist.cf
transport_maps_user.cf
virtual_alias_maps.cf
tracy@zzzzzz.ccc
virtual_mailbox_domains.cf
virtual_mailbox_maps.cf
vmail1/zzzzzz.ccc/t/r/a/tracy-2025.09.09.17.13.47//Maildir/


I found a work around by adding every email address to a recipient_access file and adding the line 

check_recipient_access hash:/etc/postfix/recipient_access,

to the smtpd_recipient_restrictions

It started to happen with other users of other domains, so it's not a single user anymore. 

Still want to find the cause, so any more tips are appreciated.

It's back to working now, but I haven't removed my fix yet.

I think the problem may be with something my cloud provider did with their networking.